What is wrong with my Opel Astra 1.4 1998 if when it is warm it start twitch it is from 1-3 thousand rpm?

If your 1998 Opel Astra 1.4 is twitching or hesitating between 1,000 to 3,000 RPM when warm, it could be due to several issues. Common culprits include a dirty or failing idle air control valve, ignition system problems (such as worn spark plugs or ignition coils), or fuel delivery issues (like a clogged fuel filter or failing fuel pump). It's advisable to have the vehicle diagnosed by a mechanic to pinpoint the exact cause.